Tripack



March .29, 1938. w. D. BALDSIEFEN r AL 2,112,226

TRIPACK Filed 00";- 24, 1936 LIGHT PERMANENT NEUTRAL- GRAY ANTI-HALO BASE BLUE-SENSITIVE EMULSION WITH REMOl/AfiLf VELLOW f/LTER DYE INCORPORATED THERE/N 'xalemv-smsmvs EMULSION CLEAR was:

REMOVAdLf RED FILTER DYE RED-SENSITIVE EMULSION CLEAR 5,455

RbEMOVAdLf GREEN/SH ANTI-HALO INVENTORS,

ATTORNEY Patented Mar. 29, 1938 UNITED STATES PATENT OFFICE 2,112,226 TR IPACK Application October 24, 1936, Serial No. 107,484

2 Claims.

This invention relates to color photographyami; more particularly to an improved tripack Prior disclosures suggest many forms of multipack embodying plates or films with emulsion and filter layers. None of these have afforded the desired sharpness in detail or uniformity in reproduction of color values. The present invention is a novel combination that overcomes these difficulties and provides a simple and efficient means for long-sought control of definition and color value which also greatly simplifies subsequent registration problems.

A principalobject of this invention is to provide an improved and simplified tripack that may be readily and successfully used by amateurs and those relatively unskilled in color photography. A further object is to provide a tripack that will afford an improved definition and control of color reproductions. Further objects will more plainly appear from the detailed description hereinafter presented.

The following preferred exemplification of this invention is given in illustration but not in limitation thereof.

The single figure of the drawing represents diagrammatically an assembled view of the novel tripack.

The front element of a preferred form of ourv improved tripack, which is positioned in the camera facing the aperture, comprises a cellulose nitrate film base, as indicated in the figure, bearing on its rear side a blue sensitive emulsion layer having a sensitivity range of 400 to 420 l. This emulsion isof the well-known positive type and contains no sensitizing dyes. Incorporated in this emulsion is a removable yellow filter dye, such as Tartrazine, Naphthol Yellow or Luxol Yellow, which disappears during processing. The film base bears a neutral gray anti-halation tint that is non-removable and may be obtained from such dyes as a combination of Resin Black and Wool Fast Blue, Nigrosine or Induline, applied so as to afford a total light transmission of approximately The intermediate element comprises a clear cellulose nitrate film base bearing on its front type and contains the usual thio-pseudo-cyanine dyes as sensitizers.

The rear element comprises a cellulose nitrate film'base bearing on its front side a red-sensitive emulsion layer having a sensitivity range of 580 to 680 mi. This emulsion is of the well-known panchromatic type and contains-the usual panchromatic sensitizers, such as known carbocyanine dyes. The rear side of the base bears a removable anti-halation coat of greenish hue, such as may be obtained by Helvetia Green or Acid Green dyes applied so as to afford a total light transmission of approximately 25%. This antihalation coat disappears during processing.

The purpose of the permanent neutral gray base at the top of our tripack is to afford positive and non-selective prevention of front halation. The direct incorporation of the yellow die in the Blue sensitive emulsion permits direct optical contact with the surface of the greensensitive emulsion. The light rays to which these two emulsions are sensitized are most easily scattered by the silver halide particles, and therefore these two emulsions must be in close contact with each other to reduce the length of path of the scattered light. The direct incorporation of the aforementioned yellow dye also acts to effectively reduce'the effect of the irridescence caused by the light striking the grains of the blue-sensitive layer.

The greenish anti-halo dye reflects light to which the panchromatic emulsion in the rear element is least sensitive, thereby affording improveddefinition in that element.

The herein described improved tripack may be exposed in an ordinary camera and developedby simple means well-known in the art of color photography. It produces such an improvement in definition and color value that amateurs are finally able with ordinary inexpensive equipment to uniformly produce the accuracy of color rendition so long desired in this art.

The above preferred embodiment is intended to be illustrative only and any modification or variation which conforms to the spirit of the invention is intended to be included within the scope of the claims.

We claim:

1. In combination in a tripack assembled and held in optical contact in the order named, a front element comprising a permanent neutralgray anti-halation film base bearing on its rear side a blue-sensitive emulsion layer containing therein a removable yellow filter dye; an intersion layer and on its rear side a removable red filter dye layer; and a rear element comprising a film base bearing on its front side a redsensitive emulsion layer and on its rear side a removable anti-halation layer of greenish hue.

2. In combination in a tripack, assembled and held in optical contact in the order named: a front element comprising a non-removable neutral-gray anti-halation film base bearing on its rear side an emulsion layer of a sensitivity range of 400 to 500 1. and having incorporated in said emulsion a removable yellow filter dye; an intermediate element comprising a clear film base having on its front side an emulsion layer of a sensitivity range of 400 to 580 up and on its rear side a removable red filter dye layer; and a rear element comprising a film base bearing on its front side an emulsion layer of a sensitivity range of 400m 680 and on its rear side a removable anti-halation layer of greenish hue.

WALTER DEWEY BALDSIEF'EN. JOHN RAU WEBER. 

